494
FXUS63 KOAX 161054
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
554 AM CDT TUE SEP 16 2025
KEY MESSAGES
- LOW END CHANCE FOR A SHOWER OR STORM ACROSS THE MISSOURI RIVER
VALLEY INTO WESTERN IOWA THIS AFTERNOON. HIGHS TODAY REACH THE
MID 80S TO NEAR 90F ALONG THE NEBRASKA/SOUTH DAKOTA BORDER.
- SHOWER AND STORM CHANCES GRADUALLY INCREASE FROM WEST TO EAST
LATE THIS EVENING. POPS PEAK AT 30 TO 60% ACROSS NORTHEAST
NEBRASKA AFTER 10 PM. SOME STORMS MAY BE STRONG.
- 60 TO 80% CHANCE OF STORMS FOR WEDNESDAY, AND CONTINUED RAIN CHANCES
THROUGH AT LEAST SATURDAY. REPEATED ROUNDS OF RAINFALL MAY
RESULT IN LOCALIZED FLOODING CONCERNS.
DISCUSSION
ISSUED AT 340 AM CDT TUE SEP 16 2025
SHORT TERM
/TODAY THROUGH WEDNESDAY NIGHT/
GOES-19 NIGHTTIME MICROPHYSICS SHOWS CLEAR SKIES ACROSS THE MAJORITY
OF OAX EARLY THIS MORNING. TEMPERATURES REMAIN MILD AS WELL, WITH
08Z METARS REPORTING ANYWHERE FROM THE LOW 60S TO LOW 70S WITH LIGHT
SOUTHEASTERLY WINDS.
LOOKING AT THE PATTERN ALOFT, H5 RAP OBJECTIVE ANALYSIS SHOWS A
CLOSED 576DAM LOW EMBEDDED WITHIN A POSITIVELY TILTED TROF WHOSE
AXIS RESIDES OVER SOUTHERN MONTANA INTO IDAHO. JUST TO THE EAST OF
THE TROF, THE FEATURE HAS ALREADY INDUCED A 1012 MB SFC LOW OVER
CENTRAL SOUTH DAKOTA. SFC OBS SHOW A COLD FRONT EXTENDING FROM NEAR
PIERRE, SOUTH DAKOTA SOUTHWEST TOWARD THE NEBRASKA PANHANDLE EARLY
THIS MORNING. THE FRONT IS PROGGED TO PUSH EAST INTO THE FORECAST
AREA BY THIS EVENING, EVENTUALLY STALLING OUT ACROSS EASTERN
NEBRASKA ON WEDNESDAY.
AHEAD OF THE FRONTAL FEATURE, EXPECT TO SEE A MIX OF CLOUDS AND SUN
THROUGH AT LEAST THE AFTERNOON HOURS TODAY AS HIGHS REACH THE
MID 80S TO NEAR 90F WITH 10-15 MPH SOUTHERLY WINDS. A FEW CAMS
TRY TO IGNITE CONVECTION ACROSS THE MISSOURI RIVER VALLEY INTO
WESTERN IOWA AFTER 18 OR 19Z, MOST LIKELY ATTRIBUTED TO SUBTLE
H8 WARM AIR ADVECTION ROUNDING THE 159DAM RIDGE CENTERED OVER
EASTERN IOWA. KINEMATIC FORCING IN THE LOW TO MID LEVELS DOESN'T
APPEAR VERY STRONG, SO CONFIDENCE IN CONVECTION DEVELOPING
ACROSS THESE AREAS REMAINS UNCERTAIN DESPITE SEEING AROUND 1,500
TO 2,500 J/KG OF WEAKLY CAPPED SFC BASED CAPE. SHEAR APPEARS
WEAK THROUGHOUT THE COLUMN AS WELL, SO CONFIDENCE IN SEEING
SEVERE STORMS IS RATHER LOW WITH THIS ACTIVITY. HAVE
COLLABORATED WITH DMX TO INCLUDE LOW END 15 TO 20% POPS ALONG
OUR SHARED BORDER AREAS FROM 19Z THIS AFTERNOON TO AROUND 02Z
WEDNESDAY.
TURNING OUR ATTENTION TO THE WEST, THE FRONTAL BOUNDARY WILL TRACK
EAST DURING THE DAY TODAY, EVENTUALLY REACHING EASTERN NEBRASKA
LATE THIS EVENING INTO WEDNESDAY MORNING. BUFKIT SOUNDINGS AND
MODEL OUTPUT SUGGEST ANYWHERE FROM 1,500 TO 2,000 J/KG OF MUCAPE
IN NORTHEAST NEBRASKA LATE THIS EVENING. HOWEVER, 0-6 KM BULK
SHEAR THROUGHOUT THE COLUMN APPEARS POOR AND WILL LIKELY LESSEN
THE CHANCE FOR SEVERE STORM DEVELOPMENT. LATEST CAM GUIDANCE
SUGGESTS THAT STORMS WILL INITIALLY DEVELOP OVER CENTRAL
NEBRASKA AND QUICKLY GROW UPSCALE INTO AN MCS AS THE 0-6 KM BULK
SHEAR VECTOR IS NEARLY PARALLEL TO THE FRONT. CAMS SHOW THE
LINE WEAKENING AS IT TRACKS EAST INTO THE FORECAST AREA LATE
TONIGHT INTO WEDNESDAY MORNING GIVEN IT RUNS INTO WEAKER
INSTABILITY AND SHEAR. HOWEVER, A STRONG STORM OR TWO WITH GUSTY
WINDS OR HAIL CAN'T BE RULED OUT. THE SPC HAS ISSUED A MARGINAL
RISK OF SEVERE WEATHER MAINLY NORTHWEST OF A LINE FROM PLATTE
TO WAYNE COUNTIES FOR THIS EVENING. POPS PEAK AT 30 TO 60%
ACROSS NORTHEAST NEBRASKA AFTER 10 PM.
MODEL GUIDANCE SUGGESTS A GRADUAL INCREASE OF KINEMATIC FORCING/Q-
VECTOR CONVERGENCE ACROSS THE FORECAST AREA FROM WEST TO EAST AS THE
FRONT PUSHES THROUGH. SO, EXPECT A GRADUAL INCREASE IN POPS LATE
TONIGHT INTO WEDNESDAY MORNING. LOWS TONIGHT WILL BE IN THE LOW
TO MID 60S.
WEDNESDAY WILL SEE THE FRONTAL BOUNDARY STALL OUT ACROSS EASTERN
NEBRASKA AS THE H5 LOW OVER THE MT/ID REGION SLOWLY EJECTS TO THE
EAST. WITH CONTINUED FORCING FOR ASCENT AND SOUTHERLY LOW LEVEL FLOW
HELPING BRING IN MOISTURE, WILL CONTINUE TO SEE A THREAT FOR POPS
FOR MUCH OF THE DAY. POPS PEAK AT 60 TO 80%, WITH THE HIGHEST POPS
EXPECTED OVER NORTHEAST NEBRASKA BY WEDNESDAY AFTERNOON AND EVENING.
A FEW STRONG STORMS COULD DEVELOP ON WEDNESDAY, BUT SIMILAR TO
TUESDAY, THE MAIN LIMITATION APPEARS TO BE THE WEAK SHEAR IN PLACE.
BY WEDNESDAY NIGHT, TOTAL QPF WILL RANGE FROM AROUND A QUARTER INCH
ALONG THE MISSOURI RIVER VALLEY, TO AROUND AN INCH ACROSS FAR
NORTHEAST NEBRASKA. IT IS WORTH NOTING THAT REPEATED ROUNDS OF
RAINFALL COULD LEAD TO LOCALIZED FLOODING CONCERNS. HIGHS WEDNESDAY
WILL BE NOTICEABLY COOLER IN THE LOW TO MID 70S ACROSS EASTERN
NEBRASKA, TO LOW 80S IN WESTERN IOWA. LOWS WEDNESDAY NIGHT REACH THE
LOW TO MID 60S.
LONG TERM
/THURSDAY THROUGH MONDAY/
THURSDAY WILL SEE THE H5 LOW STALL OUT ACROSS THE NORTHERN PLAINS,
WITH SEVERAL BITS OF VORTICITY EJECTING ALONG THE CYCLONIC FLOW.
THIS RESULTS IN CONTINUED RAIN AND STORM CHANCES FROM THURSDAY
THROUGH AT LEAST SATURDAY WHEN THE LOW FINALLY TRACKS EAST TOWARD
THE GREAT LAKES. NBM POPS PEAK AT 50 TO 60% FOR MUCH OF THE FORECAST
AREA THURSDAY, WITH AROUND 40-50% POPS BY FRIDAY BEFORE GRADUALLY
TAPERING OFF BY SATURDAY. REPEATED ROUNDS OF STORMS MAY LEAD TO
LOCALIZED FLOODING. MORE SHORTWAVES WILL EJECT FROM THE WEST AND
ENTER THE NORTHERN PLAINS BY NEXT WEEK RESULTING IN LOW END 15 TO
30% POPS.
HIGHS COOL FOR THURSDAY AND FRIDAY WITH VALUES IN THE LOW TO MID
70S. TEMPERATURES RETURN TO THE UPPER 70S TO LOW 80S FOR THE WEEKEND
INTO NEXT WEEK.
AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/
ISSUED AT 550 AM CDT TUE SEP 16 2025
VFR CONDITIONS ARE EXPECTED FOR THE DURATION OF THIS TAF CYCLE.
WINDS WILL REMAIN AT 12 KTS OR LESS AND FROM THE SOUTH, BEFORE
TURNING TO THE SOUTH SOUTHEAST BUT REMAINING LIGHT AFTER 00Z.
HAVE INCLUDED MENTIONS OF -SHRA AT KOFK AFTER 09Z AS A LINE OF
STORMS WILL EVENTUALLY MOVE FROM WEST TO EAST ACROSS THE
FORECAST AREA. EXPECT FURTHER REFINEMENTS AND ADJUSTMENTS MADE
TO FUTURE ISSUANCES REGARDING _SHRA TIMING AT KOFK AND
POTENTIAL INCLUSION AT REMAINING TERMINALS WITH THE 18Z
ISSUANCE.
OAX WATCHES/WARNINGS/ADVISORIES
NE...NONE.
IA...NONE.
DISCUSSION...CASTILLO
AVIATION...CASTILLO
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